fec: fix uninitialized rx buffer usage

The fec driver was enabling receive buffer descriptor without allocating
the buffers. Make sure the buffer descriptors are initialized to not
start receiving packets.

Open also calls fec_restart after the rx buffers are allocated. With the code
in fec_restart, it zeroes out the buffer descriptors that have just been
setup.

Signed-off-by: Rob Herring <r.herring@freescale.com>
Signed-off-by: Amit Kucheria <amit.kucheria@canonical.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/fec.c

@@ -1658,6 +1658,7 @@ static int fec_enet_init(struct net_device *dev, int index)
 {
 	struct fec_enet_private *fep = netdev_priv(dev);
 	struct bufdesc *cbd_base;
+	struct bufdesc *bdp;
 	int i;
 
 	/* Allocate memory for buffer descriptors. */
@@ -1710,6 +1711,34 @@ static int fec_enet_init(struct net_device *dev, int index)
 	/* Set MII speed to 2.5 MHz */
 	fep->phy_speed = ((((clk_get_rate(fep->clk) / 2 + 4999999)
 					/ 2500000) / 2) & 0x3F) << 1;
+
+	/* Initialize the receive buffer descriptors. */
+	bdp = fep->rx_bd_base;
+	for (i = 0; i < RX_RING_SIZE; i++) {
+
+		/* Initialize the BD for every fragment in the page. */
+		bdp->cbd_sc = 0;
+		bdp++;
+	}
+
+	/* Set the last buffer to wrap */
+	bdp--;
+	bdp->cbd_sc |= BD_SC_WRAP;
+
+	/* ...and the same for transmit */
+	bdp = fep->tx_bd_base;
+	for (i = 0; i < TX_RING_SIZE; i++) {
+
+		/* Initialize the BD for every fragment in the page. */
+		bdp->cbd_sc = 0;
+		bdp->cbd_bufaddr = 0;
+		bdp++;
+	}
+
+	/* Set the last buffer to wrap */
+	bdp--;
+	bdp->cbd_sc |= BD_SC_WRAP;
+
 	fec_restart(dev, 0);
 
 	/* Queue up command to detect the PHY and initialize the
@@ -1730,7 +1759,6 @@ static void
 fec_restart(struct net_device *dev, int duplex)
 {
 	struct fec_enet_private *fep = netdev_priv(dev);
-	struct bufdesc *bdp;
 	int i;
 
 	/* Whack a reset.  We should wait for this. */
@@ -1768,33 +1796,6 @@ fec_restart(struct net_device *dev, int duplex)
 		}
 	}
 
-	/* Initialize the receive buffer descriptors. */
-	bdp = fep->rx_bd_base;
-	for (i = 0; i < RX_RING_SIZE; i++) {
-
-		/* Initialize the BD for every fragment in the page. */
-		bdp->cbd_sc = BD_ENET_RX_EMPTY;
-		bdp++;
-	}
-
-	/* Set the last buffer to wrap */
-	bdp--;
-	bdp->cbd_sc |= BD_SC_WRAP;
-
-	/* ...and the same for transmit */
-	bdp = fep->tx_bd_base;
-	for (i = 0; i < TX_RING_SIZE; i++) {
-
-		/* Initialize the BD for every fragment in the page. */
-		bdp->cbd_sc = 0;
-		bdp->cbd_bufaddr = 0;
-		bdp++;
-	}
-
-	/* Set the last buffer to wrap */
-	bdp--;
-	bdp->cbd_sc |= BD_SC_WRAP;
-
 	/* Enable MII mode */
 	if (duplex) {
 		/* MII enable / FD enable */